This invention relates generally to injection molding and more particularly to an injection molding nozzle having an improved heating element configuration in the tapered nose portion and a method of making it.
Injection molding nozzles having an electrical heating element extending into a tapered nose portion are known in the art. The applicant's Canadian patent application Ser. No. 542,185 entitled "Coated Injection Molding Nozzle and Method" filed July 15, 1987 shows a nozzle in which the forward end of the heating element extends into a diagonal bore in the nose portion. More recently, the applicant's Canadian patent application serial number 549,517 entitled "Method of Manufacture of Injection Molding Nozzle Having Grounded Heating Element Brazed into Pointed Tip" and Canadian patent application serial No. 549,518 to Mold-Masters Limited entitled "Injection Molding Nozzle Having Grounded Heating Element Brazed into Pointed Tip" filed Oct. 16, 1987 disclose grounding the forward end of the heating element an air-hard tool steel insert which forms a pointed tip at the forward end of the nozzle. While these arrangements are indeed advantageous, they have the disadvantage for some applications that the portion of the heating element extending through the nose portion of the nozzle provides a substantially uniform amount of heat along its length.